CBQE-1119: couchbase-cli(bucketCreation, testStartStopRebalance)

tests for rebalance, rebalance-status, rebalance-stop, server-add, bucket-create commands

Change-Id: I2ceec64649ec73a15fc7abc53e16d771f6f7a37c
Reviewed-on: http://review.couchbase.org/25799
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>